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Even in Death, Carl Sagan's Influence Is Still Cosmic

Two weeks before he died, Dr. Carl Sagan dropped by to see Daniel S. Goldin, the NASA Administrator. Dr. Sagan was deathly ill. His blue jeans hung limp. He had no hair. His losing battle against the bone-marrow disease myelodysplasia had taken a heavy toll.

But his mind was ablaze.

For an hour or two in Mr. Goldin's office at the Washington headquarters of the National Aeronautics and Space Administration, Dr. Sagan, the astronomer, laid out a series of visions about the future of space exploration. So lively was the discussion that the two men continued it over dinner in nearby Georgetown.

''He was talking with intensity,'' Mr. Goldin marveled. ''A man on his deathbed. This is the Carl Sagan I love, a man so full of hope and optimism that he never gave up. He never gave up.''

That meeting was the last of dozens between Dr. Sagan and Mr. Goldin, who credits the astronomer with major NASA initiatives for this century and the next.

When Dr. Sagan died two years ago this month at age 62, most eulogies focused on his career in popularizing science and conveying the wonders of the universe to millions of people. But in addition to his celebrity, or perhaps even despite it, Dr. Sagan was a serious and gifted researcher who pushed back the frontiers of planetary science, molded a number of gifted students and wielded great influence behind the scenes in Washington. Time and again he came to the rescue of the politically beleaguered search for intelligent life in the universe.

So today his legacy lives on, most especially in the actual doing of science and space exploration, areas where his elan was mostly unknown to people who read his books and watched his television shows. Most centrally, his legacy is addressing one of Dr. Sagan's most durable curiosities -- the riddle of whether life exists beyond Earth.

As NASA prepares to mount thorough explorations of the two most likely sites in the solar system, Mars and Europa, it is Dr. Sagan's proteges who are in charge. Indeed, his greatest student may be one who never took a class, Mr. Goldin, the commander of this star fleet.

Of those who did take courses, one of the top students was Steven W. Squyres, 42. Now a Cornell University professor, Dr. Squyres chairs a 15-person NASA advisory committee on exploration of the solar system.

He also heads a 20-member NASA team designing a Martian rover meant to land on the planet in 2003, probe its terrain, drill into hard volcanic rock and fire samples back to Earth. From the rocky samples, scientists hope to extract Martian microbes, either fossil or extant, proving the reality of aliens.

Dr. Squyers said his scientific skills owe much to Dr. Sagan, including a knack for knowing what to ignore and what to watch. ''In light of his marvelous communication skills, lots of people lose sight of how he was also a hell of a physicist,'' Dr. Squyres said. ''His work could be brilliant,'' and brilliantly presented.

''Carl was able to show you how to cut to the heart of the matter. That was the most important thing he ever taught me,'' Dr. Squyres said.

Another top student is Christopher F. Chyba, 39. For NASA, he is probing even farther into the hinterlands.

He chairs a 12-person panel drafting plans for a spacecraft that the agency in 2003 wants to fire toward Europa, a large moon of Jupiter whose icy, cracked surface hints strongly of an interior ocean. NASA and many scientists want to know if the sea exists and if alien life thrives in its inky depths.

Dr. Chyba said one of most important lessons Dr. Sagan taught him was the value of raw curiosity. ''He had a willingness to address a broad sweep of issues, even if you couldn't always get answers,'' he said.

Brash and brilliant, a poor kid aiming high, Dr. Sagan entered the University of Chicago in 1951 at age 16, got a bachelor's degree in liberal arts in 1954 and one in physics in 1955, a master's in physics in 1956 and a Ph.D. in astronomy and astrophysics in 1960, ready to shake up his field.

Astronomy at the time was in love with stars and suspicious of planets, whose study had produced an embarrassment of false claims early in the century about dying civilizations on Mars. But Dr. Sagan was deeply curious about extraterrestrial life and pursued the topic with vigor, prodding others to do the same. He was rigorous, despite his enthusiasm. One of his credos, often repeated by experts, was ''extraordinary claims require extraordinary evidence.''

As a 27-year-old astronomer, he found his avocation in 1961 when he attended a small meeting with diverse experts to figure out whether a radio search for alien civilizations was worthwhile. The group decided it was, and that Earth's own galaxy, the Milky Way, in theory held up to 100,000 advanced civilizations, many with powerful transmitters and other technologies that might be detected from afar. Thus was planted an important seed.

A polymath, Dr. Sagan wrote his first scientific paper on the origin of the gene, the basic unit of heredity, in 1957. In 1962, he wrote a paper with Joshua Lederberg, a Nobel laureate in biology, on possible Martian life. In 1962 and 1963, he won an appointment at Stanford University's medical school to explore that topic.

''He knew more about biology than any astronomer I'd ever met,'' recalled Dr. Frank Drake, an astronomer and a pioneer of the extraterrestrial hunt.

Despite Dr. Sagan's devotion to aliens, his early achievements helped show that they were less likely in some places than scientists had previously thought. While in his 20's, he deduced that mysterious radio emissions from Venus were caused by surface temperatures around 900 degrees, far too hot for life.

By 1967, Dr. Sagan took aim at Mars from a post at Harvard. Some scientists said the planet's seasonal color variations were caused by plant life. But he and a graduate student, James Pollack, proposed that the variations were instead caused by wind storms and blowing Martian dust, which turned out to be right.

Dr. Sagan went to Cornell in 1968 and stayed there until he died. His influence grew as he edited a leading journal and helped found the American Astronomical Society's Division for Planetary Sciences, raising his field's status. Division membership soared from 100 or so in 1970 to about 1,400 today.

As an explorer, Dr. Sagan played important roles in helping NASA loft the world's first wave of interplanetary probes, including ones to Venus, Mars, Jupiter, Saturn, Uranus and Neptune. He was on the team that set two landers on Mars in 1976. The craft, to his dismay, found no hint of life.

Far from giving up the extraterrestrial hunt, he increasingly looked toward the stars. In 1975 and 1976, Dr. Sagan and Dr. Drake searched for alien civilizations with the huge dish antenna at Arecibo, Puerto Rico. The radio telescope, the world's largest, had never before been so used.

In 1982, Dr. Sagan rushed to the defense of such work after Senator William Proxmire tried to get it cut from the Federal budget as a waste of money. First, after a tete-a-tete, he got the Senator to end his criticism. Then, he won public backing for such hunts from 70 of the world's top scientists, including seven Nobel laureates.

''We urge the organization of a coordinated, worldwide, and systematic search for extraterrestrial intelligence,'' Dr. Sagan's group wrote in Science, the nation's foremost scientific journal.

Part of his growing influence came from the great popularity of his books, most of which were best sellers. ''The Dragons of Eden'' (Random House, 1977) won a Pulitzer Prize. Others included ''Broca's Brain'' (Random House, 1979) and ''Cosmos'' (Random House, 1980). ''Contact'' (Simon & Schuster, 1985), his only fictional work, told of a radio-telescope hunt that stumbled on an alien civilization.

Dr. Sagan became increasingly political in the 1980's. In books, talks and protests, he faulted nuclear-arms testing, the Reagan Administration's Star Wars anti-missile plan and, inspired by a dust storm on Mars, warned that nuclear war could result in a smoke-shrouded, deeply frozen Earth that he and colleagues called ''nuclear winter.''

His leap from the ivory tower to television studios and executive suites annoyed some peers. Science magazine in 1982 looked askance at The Cosmos Store, a venture Dr. Sagan set up to make cosmic books and calendars. The National Academy of Sciences, the nation's premier scientific club, landed a heavy blow in 1992 by rejecting him for membership.

''Carl was so superb at public relations that this engendered some jealousy among colleagues who weren't,'' said Elliott Levinthal, a Stanford professor who worked with Dr. Sagan for many years.

Despite the academy rebuff, he grew even more powerful. Starting in 1992, Mr. Goldin, the newly installed NASA Administrator, a former aerospace engineer and executive, consulted Dr. Sagan for advice and developed a respect for his energy and views during dozens of meetings.

The bond was strengthened by personal history. Both had grown up in New York and gone to its public schools, Mr. Goldin in the Bronx and Dr. Sagan in Brooklyn.

The most influential questions, Mr. Goldin said, had to do with the puzzle of extraterrestrial life and how best to address it. Dr. Sagan, he said, especially bore in on how to probe Mars, whose greater warmth and wetness in its early days were seen as possibly having given rise to microbes or other forms of life.

Historically, NASA had taken a Cadillac approach to space exploration, launching costly probes rarely. The more costly the probes got, the rarer and more complex they became. In 1992, only one spacecraft was scheduled to fly to Mars, a $1 billion orbiter known as Observer, the nation's first mission to the red planet in 17 years.

''His argument was that this is not a program, it's a single event, it's the last ship out of port,'' Mr. Goldin recalled. ''Although I had a lot of my own thoughts, and had talked to a lot of people, Carl convinced me I had to develop a vision and a strategy for Mars.'' By early 1993, Mr. Goldin said, a new plan was set. It featured low-cost orbiters and landers to be flown every two years as Mars and Earth came into alignment. The merit of the new approach was driven home in August 1993 when the costly Observer craft, as it neared the red planet, failed mysteriously.

The new series began last year when Mars Pathfinder landed and created a sensation with its miniature rover. Others are to follow in 1999, 2001, 2003, 2005, 2007 and so on.

More generally, Mr. Goldin said, Dr. Sagan played a vital role in getting the agency to deepen its biological roots. In 1994 and 1995, he said, he met often with Dr. Sagan and other advisers to discuss how to sharpen NASA's overall skills in examining Mars and more distant worlds for signs of alien life.

In response to the ferment, NASA planned an Astrobiology Institute, a consortium of academic and agency experts in various sciences, to address the riddle of life in the universe.

Established this year, the institute is run by NASA's Ames Research Center in California and has 11 institutional members, including teams at Harvard, the University of Colorado and the Marine Biological Laboratory in Woods Hole, Mass. Its budget, now $9 million, is expected to grow to $100 million annually.

Dr. Sagan saw little of what he helped create late in life. He died Dec. 20, 1996, at the Fred Hutchinson Cancer Research Center in Seattle, before the Mars Pathfinder landed with its Sojourner rover and the Astrobiology Institute took off.

But his students are leading the new hunt for extraterrestrial life, with Dr. Squyres focusing on Mars, and Dr. Chyba on Europa.

On May 18, Dr. Chyba wrote NASA as chairman of the panel drawing up plans for a Europa orbiter. That project, he said, was in the agency's ''greatest traditions'' of exploration, presenting large challenges as well as enormous potential payoffs.

''Should the 2003 orbiter demonstrate the existence of an ocean,'' he wrote, Europa will rapidly become ''a primary focus'' in the next century's hunt for extraterrestrial life.